The secondary battery represented by a lithium ion secondary battery used for a hybrid vehicle or an electric vehicle includes a safety valve that discharges a gas generated within the secondary battery.
For example, PTL 1 has proposed a structure in which a cover that totally covers safety valve outlets of a plurality of secondary batteries is provided to collect a gas even when the gas is discharged from any secondary battery.
PTL 2 has proposed a structure in which a connection part for connecting a gas collection part directly to a neighborhood of the safety valve formed on a contour portion of the secondary battery is provided.